Laser apparatus and electronic device manufacturing method

Abstract

A laser apparatus includes: an oscillator configured to output seed light in a pulse form; a first amplifier configured to amplify the seed light and to output first amplified light; a first beam splitter configured to split the first amplified light into first split light and second split light having energy smaller than that of the first split light; a first delay optical system configured to delay the second split light; a second amplifier configured to amplify the delayed second split light and to output second amplified light; a beam combiner configured to combine the first split light and the second amplified light and to output combined light; and a pulse stretcher configured to stretch a pulse width of the combined light.

What is claimed is: 
     
         1 . A laser apparatus comprising:
 an oscillator configured to output seed light in a pulse form;   a first amplifier configured to amplify the seed light and to output first amplified light;   a first beam splitter configured to split the first amplified light into first split light and second split light having energy smaller than energy of the first split light;   a first delay optical system configured to delay the second split light;   a second amplifier configured to amplify the delayed second split light and to output second amplified light;   a beam combiner configured to combine the first split light and the second amplified light and to output combined light; and   a pulse stretcher configured to stretch a pulse width of the combined light.   
     
     
         2 . The laser apparatus according to  claim 1 , wherein
 delay time of the second split light by the first delay optical system is equal to or higher than 60% and equal to or lower than 120% of a pulse width of a stretched first split light obtained by a pulse width of the first split light being stretched by the pulse stretcher.   
     
     
         3 . The laser apparatus according to  claim 1 , wherein
 an optical path length of the first delay optical system is equal to or longer than 90 m and equal to or shorter than 180 m.   
     
     
         4 . The laser apparatus according to  claim 1 , wherein
 an optical path length of the first delay optical system is longer than an optical path length of the pulse stretcher.   
     
     
         5 . The laser apparatus according to  claim 1 , wherein
 energy of the second split light entering the first delay optical system is larger than energy of the seed light.   
     
     
         6 . The laser apparatus according to  claim 1 , further comprising:
 a first energy sensor configured to measure energy of the first split light;   a second energy sensor configured to measure energy of the second amplified light; and   a processor, wherein   the processor controls an applied voltage of the first amplifier based on a measurement result from the first energy sensor, and controls an applied voltage of the second amplifier based on a measurement result from the second energy sensor.   
     
     
         7 . The laser apparatus according to  claim 1 , wherein
 energy of the first amplified light is larger than energy of the second amplified light.   
     
     
         8 . The laser apparatus according to  claim 1 , wherein
 the first split light is light transmitted through the first beam splitter,   the second split light is light reflected by the first beam splitter, and   a transmittance of the first beam splitter is equal to or higher than 80% and equal to or lower than 96%.   
     
     
         9 . The laser apparatus according to  claim 1 , wherein
 the first delay optical system includes a relay optical system including a plurality of concave mirrors.   
     
     
         10 . The laser apparatus according to  claim 1 , wherein
 the beam combiner brings optical paths of the first split light and the second amplified light close to each other to combine the first split light and the second amplified light, and outputs the combined light.   
     
     
         11 . The laser apparatus according to  claim 1 , further comprising:
 a second beam splitter configured to split the second amplified light into third split light and fourth split light having energy smaller than energy of the third split light;   a second delay optical system configured to delay the fourth split light; and   a third amplifier configured to amplify the delayed fourth split light and to output third amplified light, wherein   the beam combiner combines the first split light beam, the third split light which is a part of the second amplified light, and the third amplified light, and outputs the combined light.   
     
     
         12 . The laser apparatus according to  claim 11 , further comprising:
 a first energy sensor configured to measure energy of the first split light;   a second energy sensor configured to measure energy of the third split light;   a third energy sensor configured to measure energy of the third amplified light; and   a processor, wherein   the processor controls an applied voltage of the first amplifier based on a measurement result from the first energy sensor, controls an applied voltage of the second amplifier based on a measurement result from the second energy sensor, and controls an applied voltage of the third amplifier based on a measurement result from the third energy sensor.   
     
     
         13 . The laser apparatus according to  claim 11 , wherein
 energy of each of the first amplified light and the second amplified light is larger than energy of the third amplified light.   
     
     
         14 . The laser apparatus according to  claim 11 , wherein
 the third split light is light transmitted through the second beam splitter,   the fourth split light is light reflected by the second beam splitter, and   a transmittance of the second beam splitter is equal to or higher than 80% and equal to or lower than 96%.   
     
     
         15 . The laser apparatus according to  claim 1 , further comprising:
 a second beam splitter configured to split the second split light into third split light and fourth split light;   a second delay optical system configured to delay the fourth split light; and   a third amplifier configured to amplify the delayed fourth split light and to output third amplified light, wherein   the first delay optical system delays the third split light which is a part of the second split light,   the second amplifier amplifies the delayed third split light and outputs the second amplified light, and   the beam combiner combines the first split light, the second amplified light, and the third amplified light, and outputs the combined light.   
     
     
         16 . The laser apparatus according to  claim 15 , wherein
 an optical path length of the second delay optical system is longer than an optical path length of the first delay optical system.   
     
     
         17 . The laser apparatus according to  claim 15 , wherein
 the third split light is light reflected by the second beam splitter,   the fourth split light is light transmitted through the second beam splitter, and   a reflectance of the second beam splitter is equal to or higher than 20% and equal to or lower than 40%.   
     
     
         18 . The laser apparatus according to  claim 15 , wherein
 the first split light is light transmitted through the first beam splitter,   the second split light is light reflected by the first beam splitter, and   a transmittance of the first beam splitter is equal to or higher than 70% and equal to or lower than 90%.   
     
     
         19 . The laser apparatus according to  claim 15 , further comprising:
 a first energy sensor configured to measure energy of the first split light;   a second energy sensor configured to measure energy of the second amplified light;   a third energy sensor configured to measure energy of the third amplified light; and   a processor, wherein   the processor controls an applied voltage of the first amplifier based on a measurement result from the first energy sensor, controls an applied voltage of the second amplifier based on a measurement result from the second energy sensor, and controls an applied voltage of the third amplifier based on a measurement result from the third energy sensor.   
     
     
         20 . An electronic device manufacturing method comprising:
 generating a laser beam with a laser apparatus, the laser apparatus including
 an oscillator configured to output seed light in a pulse form, 
 a first amplifier configured to amplify the seed light and to output first amplified light, 
 a first beam splitter configured to split the first amplified light into first split light and second split light having energy smaller than energy of the first split light, 
 a first delay optical system configured to delay the second split light, 
 a second amplifier configured to amplify the delayed second split light and to output second amplified light, 
 a beam combiner configured to combine the first split light and the second amplified light and to output combined light, and 
 a pulse stretcher configured to stretch a pulse width of the combined light; 
   outputting the laser beam to an exposure apparatus; and   exposing a photosensitive substrate to the laser beam within the exposure apparatus to manufacture an electronic device.